Rendering terrain based on data representations of three-dimensional (3D) topographies for viewing on a computer display is known in the art. Typically, a three-dimensional terrain is represented as a collection of data points and stored in a data structure. Terrain rendering techniques generally apply some form of ray tracing to a set of data points. Known ray tracing techniques involve tracing a ray from the view point through each pixel in the display until the ray reaches the surface of the data. The primary disadvantage of ray tracing is that its implementation is quite slow, taking minutes or hours to produce an image of a single scene, even using state of the art hardware and software.